Methods and systems for heat treating a food product

ABSTRACT

Methods for heat treating food products include controlling a temperature of a heating element to a maximum temperature correlated to a desired temperature for the food product. A sensed temperature of the heating element may be used to control the maximum temperature. An oven includes a heating element and a temperature sensor configured to sense the temperature of the heating element, and a controller that limits the temperature of the heating element based on output from the temperature sensor.

This is a divisional of application Ser. No. 15/915,669 filed Mar. 8,2018, which is a non-provisional of application No. 62/468,737 filedMar. 8, 2017. The entire disclosures of the prior applications arehereby incorporated by reference herein in their entirety.

BACKGROUND

Variances in heating among and within ovens can result in less thandesirable end food products. For example, a food product may beovercooked in some portions, while undercooked in other portions. Thisis particularly the case when cooking food products of varyingthicknesses or sizes. Similarly, adjacent food products in an oven maybe overcooked or undercooked. Moreover, it is very difficult to evenlycook a food product that is placed in a conventional oven for cookingdirectly from a frozen state, especially when the product isasymmetrical, thus requiring additional time and expense to initiallythaw the food product.

Conventional ovens that heat a food product by thermal transfer of heatfrom heated air in the oven to the food product (i.e., by natural orforced air convection) often produce less than desirable characteristicsof the end product, such as unevenly cooked, undercooked or overcookedmeat, and unevenly cooked, undercooked or burned bakery goods. Inconventional ovens, cooking is generally performed by heating air to adesired temperature by way of on/off thermostatic control of a muchhotter heating element. Conventional proportionally controlled heatingovens work in a similar manner, but the heating elements are heatedproportionally to the load in the oven—e.g., the lower the air and/orfood temperature in the oven, the hotter the heating element, and viceversa. However, in all such ovens, temperature differences in the air inthe oven can be substantial. The less than optimal uniformity of theheating of the air in conventional ovens can affect the resulting cookedfood product. Thus, unless an operator is present to monitor andinterrupt or modify the cooking process, the quality of the end foodproduct may be adversely affected. Furthermore, monitoring itself mayadversely affect the cooking process or food outcome. The normalpractice of opening the oven door during cooking, such as to monitor orstir food or to turn a tray to try to even out browning, slows thecooking or baking process by reducing the temperature in the oven, oftenby 100° F. or more. Then the timing can easily get away from the ovenuser. In both on/off and proportionally controlled ovens, this alsoresults in significant increases of heating element temperature. Theheating element may become red hot, causing burning of many foods and aspike in oven temperature, and may result in charring of the food andsometimes even smoke damage to the kitchen.

Another aspect of temperature-controlled treatment of meats involves dryaging of meats such as beef, lamb, pork, fowl, game and other meats. Forexample, most fresh beef is aged (tenderized) for at least a few days,and up to several weeks, to allow enzymes naturally present in the meatto break down muscle tissue, resulting in improved texture and flavor.In these processes, the meat is maintained at a low temperature (e.g.,below 40° F., often around 28° F.) to reduce or prevent the growth ofbacteria in or on the meat during the aging (tenderizing) process. Thisprocess is generally applied to whole carcasses, primal muscles orroasts. Such processes are generally not applied to already-cut steaksor filets.

SUMMARY

Methods and ovens for heat treating food products are provided.Embodiments of methods include cooking and/or dry aging the food productby thermal transfer of heat to the food product from the air in the oventhat contacts a surface of the food product (or a cooking utensil suchas a pot or pan containing the food product) by heating that air with aheating element.

In embodiments, a food product is cooked in an oven using anelectrically energized heating element that is controlled such that itdoes not exceed a maximum temperature that is defined as the sum of (a)a predetermined temperature selected from the group consisting of (i)for a pastry food product, a temperature X that is less than a burntemperature of a surface of the food product and (ii) for a meat or fishfood product, a temperature Y that is a desired internal donenesstemperature of the food product, plus (b) a predetermined droop offsetdetermined by the characteristics of the oven.

In embodiments, a maximum temperature of the heating element iscontrolled using a sensed temperature of the heating element while heattreating the food product.

In embodiments, a meat product is tenderized, or aged, by maintainingthe meat product in an oven with a heating element for two or more hourswhile a temperature of the heating element is controlled to remainbetween limits (a) and (b), wherein limit (a) is a temperature above100° F. at which surface bacteria on the meat product do not increase,plus a predetermined droop offset, and limit (b) is a higher temperatureat which most tenderizing enzymes in the meat product are inactivated,plus the droop offset.

In embodiments, an oven includes a housing defining an interior cookingspace in which a food product may be heat treated primarily by thermaltransfer of heat from heated air in the oven to the food product, and atleast one electrically energizable heating element configured to beexposed to and heat the air. The oven includes a temperature sensorconfigured to sense a temperature of the heating element and acontroller configured to impose an upper limit on the temperature of theassociated heating element and respond to output from the temperaturesensor such that the heating element temperature does not exceed theupper limit.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of methods and systems described herein will beaddressed in connection with the Figures, in which:

FIG. 1 is a block diagram of an oven in accordance with an embodiment;

FIG. 2 is a perspective view of a range in accordance with anembodiment;

FIG. 3 is a diagram of a heating element and a temperature sensor inaccordance with an embodiment;

FIG. 4 is a diagram of a user interface in accordance with anembodiment;

FIG. 5 is a cross-sectional view of the bottom wall of an embodiment ofan oven with at least one indentation for holding water;

FIG. 6 is a cross-sectional view of a portion of an oven wall in anembodiment with an induction heating unit;

FIG. 7 is a cross-sectional view of a portion of an oven wall in analternative embodiment with an induction heating unit;

FIG. 8 is a cross-sectional view of a portion of an oven wall in anembodiment with a fan heater; and

FIG. 9 is a cross-sectional view of a portion of an oven wall in analternative embodiment with a fan heater.

DETAILED DESCRIPTION OF EMBODIMENTS

The exemplary embodiments described herein provide detail forillustrative purposes and are subject to many variations in structureand design. It should be appreciated, however, that the invention is notlimited to a particularly disclosed embodiment shown or described.Various combinations of disclosed elements and omissions andsubstitutions of equivalent elements are contemplated as circumstancesmay suggest or render expedient.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The terms “a,” “an,”and “the” herein do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced object. It will befurther understood that the terms “comprises” and/or “comprising,” whenused herein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more additional features, integers,steps, operations, elements, components, and/or groups thereof.

Various embodiments include methods for cooking a food product from anot-fully-cooked state to a fully-cooked state, including but notlimited to pastry products, meat, fish, fruits and/or vegetables. (Asused herein, unless required otherwise by the context, “fish” includesshellfish.) Exemplary methods can cook a food product in one or moreheat treating modes (e.g., baking and roasting). As used herein, apastry product is a food product formed from a dough comprising flourand a liquid such as water or milk, optionally with yeast, shortening,sugar, egg, and/or other ingredients, used as a base, body and/orcovering of the food product. Examples include, but are not limited to,breads, biscuits, cakes, cookies, doughnuts, croissants, crullers,tarts, pies (including, for example, fruit, nut, meat, fish, vegetableand/or cheese pies with top and/or bottom pie crusts), pasties, and foodproducts “en croute.”

In embodiments, a food product is cooked from a not-fully-cooked stateto a fully-cooked state in an oven using an electrically energizedheating element whose temperature is controlled not to exceed a maximumtemperature defined as the sum of:

(a) a predetermined temperature selected from the group consisting of:

-   -   (i) for a pastry food product, a temperature X that is less than        a burn temperature of a surface of the food product, and    -   (ii) for a meat or fish food product, a temperature Y that is a        desired internal doneness temperature of the food product, plus

(b) a predetermined droop offset.

In embodiments, a meat product is heat treated (e.g., tenderized, oraged) by maintaining the meat product in an oven with a heating elementfor two or more hours, such as two, three, four, six, eight, ten,twelve, eighteen, twenty-four or thirty-six hours, while a temperatureof the heating element is controlled to remain between limits (a) and(b), wherein limit (a) is a temperature above 100° F., such as above115° F. or 120° F., or between 135 or 138 and 140° F., at which surfacebacteria on the meat product do not increase, plus a predetermined droopoffset, and limit (b) is a higher temperature at which most tenderizingenzymes in the meat product are inactivated, such as about 140-145° F.,plus the droop offset.

For example, in embodiments, feedback from a temperature sensor thatsenses temperature of a heating element can be used to control a maximumtemperature of the heating element during the heat treating process.While these temperatures are well below usual heating elementtemperatures in conventional ovens, surprisingly the cooking times usingmethods of the invention may generally be the same as or similar tocooking times used in conventional oven recipes, although longer cookingtimes may be used for convenience or certain food products and foodproduct characteristics. Time is also saved by the fact that thawing offrozen food products before putting them in the oven is not necessarywhen using methods/ovens of at least some embodiments of the invention(e.g., “FROZEN-TO-FINISHED™” technology).

In addition, cooking is much more uniform within one oven, ofteneliminating the need to open the door and turn a tray of product, orbetween various ovens, utilizing embodiments of methods and ovensdescribed herein with accurate heating element temperature control. Thisalso facilitates use of the same cooking recipe for all such ovens,making the need to “learn” a new oven unnecessary.

In embodiments in which such heating element temperature control isapplied to dry aging, the temperature is well above normal agingtemperatures. Aging is vastly accelerated due to the fact that aging(both tenderizing and flavor enhancing) enzymatic processes are muchmore rapid at higher temperatures. For example, the speed of suchprocesses is generally doubled by each 10° C. (about 18° F.) rise intemperature. Thus, for example, an aging process that would take threeweeks at a normal temperature of about 28° F. will take less than eighthours at about 140° F. Aging of meat products can thus be accomplishedin a very short time—e.g., between breakfast and dinner—by implementingmethods of this aspect of the invention, allowing consumers or foodretailers to purchase cheaper, tougher cuts of meat and tenderize themon demand without waiting days or weeks for the tenderization to becompleted. In embodiments, the aging temperatures are maintained for atleast two hours, preferably at least six or eight hours, or longer(e.g., 12, 18, 24 or 36 hours).

By practicing various embodiments, characteristics of the food productsmay be established and/or maintained. For example, cooking in accordancewith one or more embodiments can control the external surface and/orinternal doneness of a food product to produce and maintain (withoutsubstantial degradation that would have an adverse effect),functionality, taste, texture, and/or color (e.g., brownness) of theproduct over time, with substantial flexibility in the cooking time ofthe product. The food product may, for example, be heat treated to adesired level of doneness without any portion of the food productreaching a temperature that would produce a burned surface (e.g.,providing a crispy, but not burnt, outside surface of a cookie, or anevenly done but not burnt pie crust over, under or around a filling). Inaddition or alternatively, heat treatment in accordance with one or moreembodiments can control the internal doneness of the food product tohave a doneness gradient in the food product (e.g., from medium welldone near the surface to medium rare at the center of a cut of meat), orto be uniform substantially throughout the food product (e.g., mediumrare from edge to edge of a roast) by continuing to heat treat the foodproduct until a uniform internal temperature is reached in the foodproduct. For example, a roast may be cooked to a uniform “medium-rare”doneness from edge to edge, with only the surface being browned due,e.g., to the Maillard and/or other reactions. Using dry agingembodiments of methods of the invention, meat can be aged and cooked attemperatures of the heating elements that accomplish both aging andcooking, or aged at a lower temperature and then cooked.

In embodiments, the heat treating is performed with minimal venting ofair from the oven, for instance with a nominally unvented oven or byclosing down the vent(s) of a vented oven (subject to enough venting toprovide pressure relief) during heating-element-temperature-limited heattreatment. This can help increase the temperature uniformity within theoven, reduce waste of energy, and reduce cooking and/or aging times.Cooking with a closed down vent or slight venting in combination withplacing water in the oven before or during cooking can be particularlyuseful in reducing cooking times by providing superheated steam thatfacilitates heat transfer in the cooking space of the oven.

By practicing one or more embodiments, a food product in anot-fully-cooked state at any temperature, including but not limited tostarting as frozen, refrigerated or room temperature, raw or partiallycooked, may be cooked to a fully-cooked state by controlling thetemperature of the heating element to heat treat the entire food productto a desired level of doneness, which may be the same or differentthroughout the inside of the food product (based on a cook time) asdescribed above. For example, at a given oven temperature, some productshave different heating requirements in different portions. For example,a pie with a flanged (e.g., fluted) crust may need to stay in the ovenlonger than necessary to cook the crust in order to thaw and fully cookthe filling. For example, the crust may be fully cooked when it reaches350° F., while the filling may take much longer (possibly includingthawing time) to reach a desired temperature of 200° F. With methods ofthe invention, the oven can be set at 350° F. (with the heating elementcontrolled, for example, not to exceed about 350° F. plus droop offset),and the pie may be left in the oven until the filling reaches thedesired temperature. In such a “safe” mode, even a thin flange of thecrust can be maintained at a cooked but not burnt temperature long afterit is fully cooked, allowing completion of the thawing and/or cooking ofthe filling without burning of the crust. Similarly, while the center ofa frozen roast or fish will take much longer than the surface to cook toa desired temperature, the portions of the food product nearer thesurface will not exceed a pre-set doneness level. Thus, the temperatureof the initial food product and asymmetry of the food product do notadversely affect the outcome of the heat treatment. Separate thawingtimes and actions are not required. For example, with an asymmetric foodproduct that is to be brought to a uniform temperature, smaller orthinner parts of the food product can be kept at the desired degree ofdoneness while larger or thicker parts of the food product continue tothaw and cook to that level of doneness. For example, a fish filet suchas a salmon filet with a thin section and a thick section, or a roastwith a large-diameter end and a small diameter end, can be cooked fromfrozen or another temperature until the thicker or larger section isfully cooked, without overcooking the thinner or smaller section.

As used herein, “fully-cooked state” generally entails a state ofcooking at which the product could normally be intended to be consumed,but does not preclude further heat treatment of the food product. Forexample, a fully-cooked meringue pie may be subjected to brief broilingto singe the tops of the meringue, or a fully-cooked piece of meat orfish may be additionally grilled to add grill flavoring and/or markings,or further cooked to a different greater doneness level—e.g.,fully-cooked meat at a state of rare doneness could subsequently befurther cooked to a state of medium-rare, medium, medium-well or welldoneness. “Not-fully-cooked state” as used herein could encompass, forexample, raw or raised-but-not-fully-cooked dough, meat or fish, or apreviously partially-cooked product such as rare meat as discussedabove, or a pie in which filling materials have previously been at leastpartially cooked.

In embodiments, control of heat treating may include an initial processof preheating air in the oven to a desired heat treating temperature. Inembodiments, a food product is primarily heated by thermal transfer ofheat to the food product from air in the oven by heating the air with anelectrically energized heating element that is exposed to that air—e.g.,by natural or forced air convection. In embodiments, preheating of theoven and/or air in the oven is performed with a heating element at ahigher temperature than the limited temperature described above. Thismay be accomplished with either the same or a different heating element,and may be monitored and controlled based on feedback from a temperaturesensor that senses temperature of the oven air. Preheating may have someeffect on a surface of a food product that is present in the oven duringpreheating, depending on the susceptibility of the food product to ahigher temperature at the beginning of the heat treatment. However, inmuch cooking, oven preheating has almost no effect on the surface of thefood product due to the initial low temperature and high moisturecontent of the food product. For food products that may be adverselyaffected by preheating times and temperatures, the preheating ispreferably partially or fully completed before the food product isplaced in the oven. For food products that are not adversely affected bypreheating times and temperatures, the preheating may be begun and/orcompleted before or after the food product is placed in the oven.

During, and preferably throughout, cooking after any preheating,exemplary methods control a maximum heating element temperature not toexceed the sum of an outside surface burn temperature of the foodproduct plus a predetermined droop offset. “Droop offset” refers to aninherent loss of heat energy involved in the transfer of heat from aheating element to and through air, and is characteristic of ovendesign. In general, ovens of the same design will have the same or verysimilar droop offset. Particularly in combination with the precise heatelement temperature control available in embodiments of sensors andcontrollers of the current disclosure, this allows for improveduniformity of cooking conditions among ovens of the same model. Inembodiments, a droop offset may be as high as 30° F. or more, such as25-30° F. in a toaster oven, or 5, 10 or 15° F. in other ovens such ashome and commercial ovens. Droop offset may be at the higher levels in,for example, vented ovens like toaster oven or other ovens with the ventopen and at the lower levels in minimally vented and well insulatedovens. In addition, droop offset correlates to heat treatingtemperatures. Thus, for example, the droop offset may be much lower,e.g., below 5° F., at aging temperatures or cooking temperatures forsome meat products.

Temperatures useful in embodiments include the entire temperature rangeof the oven, and may be based on the food product and temperature calledfor by the recipe being followed. For pastry products, usefultemperatures include, for example, 225° F., 250° F., 275° F., 300° F.,325° F., 350° F., 375° F., 400° F., or 425° F. (plus droop offset). Mostpastry products will burn above 450° F., and most sugary pastry productswill burn at and above 400° F. Burning the food product in variousembodiments means heat treating the food product to a temperature (“burntemperature”) at which an outside surface of the food product has alevel of doneness or darkness that is an undesirable, such as cooked toa burnt flavor, ashy texture, and/or undesired dark brown or blackcolor. As an example, sugary pastry products such as cookies, cakes anddessert pies are generally considered too dark, and thus burnt, at asurface temperature of 400° or above, such as 450° F. Low sugar (e.g.,no-sugar-added) pastry products such as some biscuits or meat/vegetablepie crusts may be cooked at higher temperatures such as 400 or 425° F.without burning. In embodiments, a signal such as a “NO BURN™” lightwill go on for a temperature setting of 300-375° F. (plus droop offset),and will go off above a set temperature limit such as 375° F. (plusdroop offset) to indicate that temperature control in accordance withthe described methods is being implemented in a range that willgenerally prevent any burning of pastry products.

For dry aging meat products, the temperatures of the heating elementsand the aging time will depend on the meat being treated (e.g., age ofthe animal, grade of the meat, such as corn-fed versus grass-fed beef,type of meat such as beef versus pork, etc.), the size of the meatproduct, and the desired finishing temperature. For example, grass-fedbeef that is to be finished at medium rare or more may be aged atheating element temperatures of 135-140° F., such as 138-140° F., (plusdroop offset) for six to twenty-four hours or at about 120-125° F. fortwelve to thirty-six hours, whereas corn-fed beef can be aged at suchtemperatures for shorter periods of time, and beef that is to befinished in a more rare state should be aged at the lower temperatures.Such times and temperatures will work similarly for pork and other meatsthat are to be cooked to higher temperatures. Aging embodiments can beapplied to whole muscle meat, or to smaller pieces of meat such asroasts and steaks (e.g., steaks cut to less than about 1, 2 or 3 inchesthick. It has also surprisingly been found that taste and texture aresignificantly improved by aging at 130-138° F., such as 134-138° F. or134 to 136° F., even compared to aging at 140° F. (heating elementtemperatures plus droop offset).

Various embodiments allow for the control of the temperature of theheating element based on, for example, either a pre-set or userdesignated surface temperature of the food product and/or degree ofdoneness for the food product. For example, the oven may include a userinterface with an input structure (e.g., touch pad, button or dial) thatis simply labeled “bake” or “NO BURN™” or “Golden Brown” as an indicatorthat baking is being done and a method as described herein is beingimplemented to avoid burning of the food product. In such embodiments,the oven target temperature (e.g., recipe temperature) and heatingelement limit (before accounting for droop offset) may be, for example,preset at 350° F. However, some users may prefer a product that islighter or darker brown than provided by a 350° F. surface temperature.Thus the user interface may further include input structures that allowadjustment of the heating element temperature, for example in 10° F. or25° F. increments, preferably up (or down) to a predetermined limit suchas, for example, two increments, a total of 50° F., or not above 400° F.or 425° F. Such input structures (e.g., buttons, touch pads or dials),could, for example be labeled “+” and “−” or “Lighter” and “Darker” forsimplicity of understanding. In embodiments, however, the actualtemperature setting change may or may not be displayed to the user.

In cooking of meats (including but not limited to red meat and poultrymeat) and fish (including but not limited to fin fish and shellfish),various embodiments achieve even doneness regardless of thicknessvariations and without any exterior surface burning or overcooking asdiscussed above.

In embodiments, a user can set a doneness of the product using a userinterface that includes user input structures that identify traditionaldoneness levels (e.g., rare, medium rare, medium, medium-well, or welldone). In such embodiments, the heating element maximum temperature maybe set at a droop offset plus the temperature at which the meat or fishof interest exhibits such characteristics, for example using USDAguidelines. The temperature values may be stored in a table, such aswithin a memory of a controller (or in a database) of the oven and usedto set a limit on the heating element temperature.

For example, in some embodiments, the preset product temperatures fordifferent levels of doneness for different food products may beestablished as follows, generally within ±2-5° F.:

Beef—Rare 130° F.;

Beef—Medium-Rare 140° F.;

Beef—Medium 150° F.;

Beef—Medium-Well 155° F.;

Beef—Well 160° F.;

Beef—Dry and tough above 160° F.;

Beef—Stewed, Pot Roasted, “boiled” or “steamed” (beef in water with atleast some salt) around 190° F.;

Poultry (White meat)—Done and juicy 158-160° F.;

Poultry (Dark meat)—Done and juicy 168-170° F.;

Pork Loin—Done and juicy 160° F.;

Pork Shoulder—Done and juicy 168 to 170° F.;

Lamb—same as beef and other red meats;

Fish (not Tuna, Salmon, Swordfish and Shark)—Done, moist and flaky 160°F.;

Tuna, Salmon, Swordfish and Shark—Done, moist and flaky 140° F.;

Lobster Tail—Done, moist and tender 170° F.;

Lobster Claws—Done, moist and tender 180° F.

Accordingly, various embodiments can be applied to the cooking (orthawing and cooking) of different types of meat, for example, beef,veal, pork, mutton, lamb or poultry. Cooked temperatures for the variousmeats or fish may be set as desired or needed, such as based on typicalminimum cooked temperatures. In embodiments, user interfaces will allowa user to set a desired doneness temperature. This can be particularlyuseful, for example, in settings where a cooked product is beingprepared for later additional cooking, such as on an indoor or outdoorgrill or under a broiler.

In embodiments, heat treatment of a food product may be maintained foran extended time period without overcooking and without burning theoutside surface of the food product, or even with little or no cooking(e.g., in the case of dry aging of meat).

Thus, in operation, while often not necessary, heat treatment may beperformed for a longer time period than in a conventional oven (e.g., upto 300% or more longer for cookies and up to four or more times longerfor meat) without substantial degradation of the desirablecharacteristics of the food product. Thus strict compliance with recipetimes for food products need not be maintained, allowing, for example,baking of different sized products or different content productstogether in the same oven without burning any of the products in theoven, and eliminating the need for careful monitoring of the foodproduct (which elimination as described above may actually shorten therequired cooking time). The heat treatment time may be the normalcooking or baking time (such as recommend by a recipe) or longer ifdesired. A longer heat treatment time may be used, for example, when itis desirable to keep meat at a desired edge to edge doneness, either forprecooking, for keeping the meat warm without increasing doneness whileportions but not all of it are served, or for keeping the meat warmwithout increasing doneness until it is convenient to serve it (e.g.,cooking for an entire workday and having the meat ready at the desireddoneness at dinner time). (Similarly, stew, pot roast, and other fooditems can be cooked in a covered pot within the oven with a very longcooking time such as morning until dinner time.) As another example, abatch of steaks could be precooked to and held at a “rare” state inadvance of the cook receiving an indication of the preferences of theconsumer of each steak. When those preferences are received, the steakscould be quickly heated to other levels of doneness according to theindividual preferences, or, for example, finished on a grill. However,even meat cooked for a shorter period of time (e.g., less than the timethat would result in an edge to edge medium done beef roast), will havethe selected level of doneness near the surface and a normal gradient ofdoneness toward the center (such as from medium near the surface to rarein the center).

In some embodiments, particularly where a food product is normally heattreated for an extended period of time, water may be placed in the oven,but not in contact with the food product, to prevent or reduce dryingout of the food product, for proofing, and/or to expedite cooking. Forexample, the oven may include or contain a structure (e.g., a pan orcontainer, or an optional indented surface such as annular indentation520 and/or central indentation 530 in the oven bottom wall 510 as seenin cross section in FIG. 5 ) that holds water and allows the water toevaporate. This will raise humidity in the oven to prevent drying and/orfor proofing, and will also allow the vapor to contact the food productin the air within the oven, optionally at or above boiling temperaturesas superheated steam. As noted above, this may shorten the requiredcooking time for various food products.

In embodiments, the temperature of the heating element may be controlledusing the sensed surface temperature of the heating element. Thatsurface temperature may be sensed by a temperature sensor that isoperatively coupled to a surface of the heating element (e.g., incontact directly or through a thermal contact device such as a metalclamp or strap with, or remote but focused on, one or more portion ofthe heating element). In embodiments, the sensed temperature may be asensed internal temperature of the heating element that may be acquiredby integrating a portion of the temperature sensor into the heatingelement (e.g., a sensing tip embedded within the heating element).Output from the temperature sensor may be provided as input to acontroller that limits or turns off the energy delivered to the heatingelement to heat it.

In embodiments, one or more air temperature sensor may also be providedin an oven. Output from the air temperature sensor(s) may be provided asinput to the controller to control the temperature of the heatingelement(s) when the limiting function is disabled, for example duringfast preheating or during use of the oven as a normal oven without theabove-described temperature control in effect. This may be desirable forsome users and some heat treating operations, such as broiling orhigh-temperature roasting as well as for fast preheating.

In embodiments, the heating element is continuously or intermittentlyenergized to keep the heating element at or near the set temperature.For example, once heated, the controller can maintain energization ofthe heating element to keep its temperature within no more than a fewdegrees (e.g., ±5° F. or 2° F. or less) below the temperature limit, andto bring the heating element temperature back up to that range if it iscooled during the heat treatment (e.g., by opening of the oven door orinsertion of a cold food product by a user). In embodiments, thecontroller applies intermittent thermostatic energization of the heatingelement, such as with a time delay to avoid chattering.

Various embodiments include an oven 100, such as illustrated in FIG. 1for heat treating food products. The oven 100 may for example be ageneral purpose domestic oven (e.g., natural or forced air convectionhome kitchen range, countertop or wall oven) or a general purposecommercial oven (e.g., a commercial bakery or restaurant general purposeoven), self-cleaning or non-self-cleaning. As used herein, “generalpurpose oven” signifies an oven that is capable of, for example,warming, baking, roasting and broiling. Alternatively, the oven may be aspecial purpose commercial oven. For example, some special purpose highvolume baking ovens include a rotating rack upon which pastry productsare placed for baking. Such an oven includes a mechanism for rotatingthe rack to ensure even browning of the products. By incorporating thetemperature control features disclosed herein into such an oven, theneed for such a rotation mechanism could be eliminated.

The oven 100 in embodiments is configured to implement one or moremethods disclosed herein. In the embodiment of FIG. 1 , the oven 100includes an insulated housing 102 (e.g., double wall insulated housing)defining an interior space in which a food product 104 (e.g., pastryproducts, meat or fish) is placed to be heat treated. The oven 100 maybe controlled in accordance with various method embodiments describedherein.

With reference again to FIG. 1 , the oven 100 includes within thehousing 102 a first heating element 106 and a corresponding firsttemperature sensor 108. As shown in FIG. 2 , the heating element(s)could be at the bottom of the oven as at lower heating element 202, thetop of the oven as at upper heating element 204 (dotted lines being usedhere to show its location below the top surface of the oven), and/or atone or more sides of the oven. Any suitable electrically energizableheating elements may be used. For example, the electrically energizableheating element(s) may be a resistance-heating element such as aconventional sheathed nichrome heating element at one or more side, topand/or bottom wall of the oven. Alternatively, as shown in FIG. 6 andFIG. 7 , the heating element(s) may be one or more induction heatingelement such as an induction plate 610 that may be within the cookingspace 206, or an induction plate 710 that forms a top, bottom and/orside oven wall exposed to the cooking space 206. The induction plate maybe associated with an induction coil 620 within a space above, below,beside or behind an interior wall of the oven housing 102. Athermal/dielectric insulator 630 keeps the induction coil 620 outsidethe cooking space 206 both electrically and thermally, so that theinduction coil 620 only energizes (heats) the induction plate and theoven air in contact with it. (FIGS. 6 and 7 show such a system on arepresentative top, side or bottom wall of housing 102.) In embodiments,such as the alternative embodiments of FIGS. 8 and 9 , a forced airconvection system may include a fan heater 810 in which the firstheating element 106 and first temperature sensor 108 are inside and/oroutside the cooking space 206, and fan 820 blows air over heatingelement 106 and throughout the cooking space 206 by way of air passages830 and 840 through baffle 850 to heat the food product. In embodiments,the bottom of the oven cooking space is free of heating elements,thereby allowing a water containment area such as annular indentation520 or central indentation 530 (FIG. 5 ) and/or foil or the like dripprotector to be located at the bottom of the oven without impairing theheating function.

In various embodiments, as discussed in more detail herein, firsttemperature sensor 108 is operatively coupled to one or more firstheating element 106 to sense (e.g., measure or detect) a temperature offirst heating element 106, such as by contact with a surface of firstheating element 106. In some embodiments, temperature sensor 108 maymeasure or detect the temperature within first heating element 106, suchas having a measurement or detection portion inside first heatingelement 106, as further discussed below.

The oven 100 of FIG. 1 further includes a controller 110 coupled tofirst heating element 106 to selectively limit a temperature of firstheating element 106, for example in accordance with one or more of theabove-described methods. For example, a feedback control arrangement maybe provided as discussed herein, wherein the controller 110 adjusts acontrol signal to (e.g., voltage applied to) first heating element 106to limit the temperature of first heating element 106 based on a setcooking (e.g., recipe) temperature and/or a set internal temperature ofa food product to be heat treated, plus droop offset, as describedabove. In embodiments, the temperature of first heating element 106 iscontrolled based on feedback temperature information of a sensedtemperature of a surface of first heating element 106 from temperaturesensor 108.

With the temperature feedback information from temperature sensor 108,the heat treatment can be controlled by controlling a maximumtemperature of first heating element 106 and maintaining first heatingelement 106 at or near that temperature. Embodiments include but are notlimited to a close and sensitive on-off response to the sensor (e.g.,with a 2° F. or less span) with a minimum time delay (e.g., 10 or 20seconds) to prevent control chattering. Proportional and tuned controlsmay be used, but are often less reliable as they tend to be sensitive toambient temperatures, which can be extreme in a kitchen.

The oven 100 further includes a user interface 112 coupled to thecontroller 110. The user interface 112 is configured to receive a userinput, such as a desired level of doneness for a food product 104 asdiscussed herein. In some embodiments, the user interface 112, as shownin more detail in FIG. 4 , may include a bake or “NO BURN™” interfacethat when activated by way of an input structure 112 a (engaged by auser by, e.g., depressing a button, turning a dial, or touching atouch-sensitive pad), initiates one or more methods disclosed herein toheat treat the food product with the temperature of the heating elementlimited as described above. An indicator such as a “NO BURN™” light maybe activated when the oven is operating according to a “safe” mode asdescribed in more detail above. When de-activated (which may be manuallyor automatically performed, including, for example, by changing thesettings of temperature and/or mode), the user activated imposition ofan upper temperature limit may be canceled or removed. In someembodiments, this simplified interface results in an approximately 350°F. plus droop offset temperature of heating element 106, since very fewfoods will burn at their surface at or below this temperature. However,such an interface may be correlated to other temperatures such as thosedescribed above. The user interface 112 may include, in someembodiments, “plus” and “minus” or “darker” and “lighter” inputstructures 112 b and 112 c as described above (e.g., non-numericalcontrols that may be activated to adjust a level of doneness orbrownness of the product per a recipe or the user's experience), whichincreases or decreases a controlled temperature to change the maximumtemperature of the heating element (with or without displaying theadjusted temperature). Similarly, meat/fish “doneness” input structuresmay be provided as described above, for example by way of a button, dialor touchpad. These simplified systems are particularly useful in homeovens. In various embodiments, numerical controls 112 d for adjustingthe temperature as would conventionally be provided on an oven are alsoincluded. This may be useful in commercial ovens as well as home ovens.

In some embodiments, the oven 100 of FIG. 1 may optionally include oneor more second heating element 114, for example upper heating element204 in FIG. 2 that may be configured as a broiling heating element. Forexample, in some embodiments, the first heating element 106 may beconfigured to heat up to 500° F., while the second heating element 114is configured to heat up to 800° F. or more. The second heatingelement(s) 114 in various embodiments may have an optional secondtemperature sensor 115 for use as described above, and/or may be usedfor preheating as discussed herein or for broiling, browning, and/orother heat treating, if desired. In some embodiments, preheating and/orother heat treatment may be accomplished by deactivating the heattreating control based on feedback temperature information from theheating element temperature sensor 108 and/or optional secondtemperature sensor 115. During such deactivation, feedback control may,if desired, be provided based on output from optional oven airtemperature sensor 116.

As noted above, the oven 100 may optionally include an optional oven airtemperature sensor 116 that senses the temperature of air in the cookingspace 206 within the housing 102. Air temperature sensor 116 is not incontact with the first or second heating elements 106 and 114, butinstead measures the temperature of air within the housing 102 as wouldbe provided by conventional oven temperature sensing arrangements. Forexample, the temperature sensor 116 in various embodiments isoperational when the “NO BURN™” feature is not operating and the oven100 is operating in a conventional operating mode, such as to cook aroast conventionally in the oven 100 or during preheating.

The various components and elements of the oven 100 may be positionedand arranged as desired or needed, such as based on the configuration orcooking requirements for an oven. For example, FIG. 2 illustrates arange 200, which may include the oven 100.

In the range 200, range top cooking burners or “eyes” are notillustrated, but could be provided on a top surface of the range 200. Inthe illustrated embodiment (and with reference also to FIG. 1 ), therange 200 in various embodiments comprises a minimally vented oven thathas small vents or relies on the door to be an outside vent frompreferably insulated housing 102 or has one or more optionally closablevents 201, such as are often provided in self-cleaning ovens when thedoor is locked. A lower heating element 202 is located at a bottomportion of the range 200 in the air space 206, and is configured as thefirst heating element 106, and upper heating element 204 (shown inphantom lines) may be located at, or near but spaced apart from, a topportion of the oven of range 200 and configured as the second heatingelement 114. In some embodiments, different configurations of the range200 may be provided or the various embodiments may be implemented indifferent ovens.

A stationary but preferably removable rack or racks 208 may bepositioned within the oven of range 200, and may be movable to differentheights.

In the embodiment of FIG. 2 , the temperature sensor 108 is attached toa surface of the lower heating element 202 to sense (e.g., measure ordetect) the temperature of the lower heating element 202.

In the embodiment of FIG. 3 , temperature sensor 108 is attached to asurface of an end portion 300 of a heating element 106. However, itshould be appreciated that the temperature sensor 108 may be located ata different portion of the heating element 106/114. Also, additionaltemperature sensors 108 may be coupled to the heating element 106, suchas at different spaced apart locations along the surface of the heatingelement 106. The number and location of the heating elements may beprovided based on, for example, the configuration, including the size,of the oven cooking space 206 (shown in FIG. 2 ).

Optionally, one or more temperature sensor 115 could also, oralternatively, be operatively associated with the upper heating element204 to sense its temperature and provide input to the controller 110 asshown in FIGS. 1 and 2 . In such embodiments, the system could operateas discussed herein vis-à-vis the first heating element 106. Due to itslocation at the top of the oven, it may be acceptable to operate theoptional upper heating element 204 at a higher or lower temperature(e.g., up to 10-15° F.) than the temperature of the lower heatingelement 202. Hotter is particularly useful in vented ovens, whereascooler is particularly useful for, e.g., certain poultry products andcookies. For example, turkeys (and most poultry) require lower cookedtemperature of the white meat while browning the skin and highertemperature of the dark meat for it to be fully cooked. When cookingwhole poultry in an embodiment of an oven with the described control onupper and lower heating elements, one may set a lower temperature forthe upper heating element 204 than for the lower heating element 202,and cook the turkey with the breast up direct to done juicy tender whiteand dark meat and nicely browned skin. Turkey also benefits from makingthe oven minimally-vented or relying on the door to move to vent extraair and steam when water is placed in the oven and superheated steamcooks the turkey. This results in turkeys cooking much faster. Cookiesmay also be baked much more conveniently and consistently with an upperheating element temperature and higher lower heating element temperaturecontrolled in accordance with methods described herein. In aconventional oven, the cookie bottom is browned by the pan and thetemperature of the oven, and cooking of the cookie top is stopped intime for the cookies to have the appearance and texture of an oven 25°F. lower in temperature. The oven temperature, cookie size and timingall have to be just right. With the herein-described oven control,preferably with venting, cookies of any size can be baked to perfectionand with significant timing forgiveness, and with no surface burning.

The temperature sensors 108 and 115 may be any suitable sensor, such asa thermistor, a thermocouple, or a resistance temperature detector(RTD), such as a platinum RTD including platinum thin film or wirecoils. An RTD operates by supplying a constant current and measuring aresulting voltage drop across a resistor 302 (FIG. 3 ), which can thenbe used to determine a resistance value used to determine temperatureusing techniques known in the art. As should be appreciated, differenttypes of temperature sensing devices may be used. For example, thetemperature sensors 108 and 115 may be the same or different, and may beany type of temperature sensing device that is robust enough for theoven environment. Thus, for example, a very robust (or remote)temperature sensor should be used in a self-cleaning oven that reachesvery high temperatures such as 900° F. or more. In some embodiments, thetemperature sensor may be a remote temperature sensor that focuses onthe heating element (e.g., an infrared detector focused on the heatingelement). This can permit the temperature sensor to be protected fromthe more extreme temperature portions of the oven.

The shape and size of the first heating element 106 and the secondheating element 114 may be selected as desired or needed. Thus, theshape of these elements in the figures is merely for illustration. Forexample, in some embodiments as shown for example in the lower heatingelement 202 of FIG. 2 , a minimum surface area of the first heatingelement 106 is selected to minimize the cost of the heating element. Thesurface area may be selected based on the heating requirements, theconfiguration of the oven, and/or other factors. The larger the surfacearea of the first heating element, the more energy can be transferred tothe oven and the faster the food product will be heated. As the productcooks, the energy required to keep the cooking process going diminishesdramatically. Using a conventional heating element, generally selectedfor least cost by the manufacturer, will work passably well, especiallywith preheating as described above. When a larger surface area heatingelement is used, the oven is likely to be faster even than aconventional oven counterpart in which the heating element turns red hotwhen energized.

In some embodiments, the first heating element 106 is substantiallylarger, for example, 50% to 100% more surface area or more, than aconventional heating element. In some embodiments, the first heatingelement 106 is sized to cover or encompass substantially all of a top,bottom and/or side wall of the oven 200. For example, a larger surfacearea resistance heating element as shown for the upper heating element204 of FIG. 2 or the heating element 106 of FIG. 3 may have turns spacedapart by 4 inches or less substantially all the way across a bottom,side and/or top wall of the oven cooking space 206. With, for example,an induction heating system, a large surface-area induction plate in theoven or formed as one or more oven interior top, bottom and/or sidewalls could be the first heating element 106, as illustrated in FIGS. 6and 7 .

One or more embodiments can comprise one or more microprocessors (whichmay be embodied as a processor) and a memory, coupled via a system bus,which may be embodied as or form part of the controller 110 shown inFIG. 1 . The microprocessor can be provided by a general purposemicroprocessor or by a specialized microprocessor (e.g., an ASIC). Inembodiments, the controller 110 can comprise a single microprocessorwhich can be referred to as a central processing unit (CPU). In otherembodiments, the controller 110 can comprise two or moremicroprocessors, for example, a CPU providing some or most of thefunctionality and a specialized microprocessor performing some specificfunctionality. A skilled artisan would appreciate the fact that otherschemes of processing tasks distributed among two or moremicroprocessors are within the scope of this disclosure. The memory cancomprise one or more types of memory, including but not limited to:random-access-memory (RAM), non-volatile RAM (NVRAM), etc.

Block diagrams in the figures illustrate the architecture,functionality, and operation of possible implementations of systems andmethods according to various embodiments of the present disclosure. Inthem, each block may represent a module, segment, or portion of code,which comprises one or more executable instructions for implementing thespecified logical function(s). Each block, and combinations of blocks,can be implemented by special purpose hardware-based systems thatperform the specified functions, or combinations of special purposehardware and computer instructions.

At least some of the present disclosure is described herein withreference to methods and components that can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions specified herein.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions that execute on thecomputer or other programmable apparatus provide processes forimplementing the functions specified herein. When implemented in one ormore embodiments, this results in a transforming or converting a generalpurpose computer/processor/hardware to a specializedcomputer/processor/hardware that improves the technological art.

A very simple control plus a manual and a thoughtful cook is all that isneeded to implement almost all the features of this technology in even adomestic oven.

The description of the present disclosure has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to embodiments in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The embodiments were chosen and described in order to explain theprinciples of embodiments and practical application, and to enableothers of ordinary skill in the art to understand embodiments withvarious modifications as are suited to the particular use contemplated.

What is claimed is:
 1. An oven, comprising: a housing defining aninterior cooking space; an electrically energizable heating elementexposed to air that is in or enters the interior cooking space andconfigured to heat that air; a temperature sensor configured to sense atemperature of the heating element; and a controller configured toimpose an upper limit on the temperature of the heating element andrespond to output from the temperature sensor such that the heatingelement temperature does not exceed the upper limit while the oven heattreats a food product primarily by thermal transfer of heat from the airheated by the heating element to the food product by natural or forcedair convection; wherein the controller is configured to set the upperlimit of the temperature of the heating element to be a set cookingtemperature and/or a set internal doneness temperature of a food productto be heat treated, plus a predetermined droop offset of the oven thatis an inherent loss of heat energy involved in the transfer of heat fromthe heating element to and through the air and is characteristic of theoven.
 2. The oven of claim 1, further comprising a user interface thatcomprises an activation input structure by which a user can activateimposition of the upper limit by the controller.
 3. The oven of claim 2,wherein the user interface comprises a deactivation input structure bywhich imposition of the upper limit by the controller can bedeactivated.
 4. The oven of claim 3, wherein the activation inputstructure and the deactivation input structure are a same on-offstructure.
 5. The oven of claim 1, further comprising a user interfacethat comprises numerical controls for adjusting the set cookingtemperature and/or set internal doneness temperature.
 6. The oven ofclaim 1, further comprising a user interface that comprises a labeledcontrol for adjusting the set cooking temperature and/or set internaldoneness temperature to a pre-set temperature.
 7. The oven of claim 1,wherein the set cooking temperature does not exceed 425° F., the setinternal doneness temperature does not exceed 180° F., and the droopoffset does not exceed 30° F.
 8. The oven of claim 3, wherein the userinterface is configured to be operated by a user to deactivateimposition of the upper limit by the controller throughout preheating ofthe oven.
 9. The oven of claim 1, wherein the controller is configuredto automatically deactivate imposition of the upper limit throughoutpreheating of air in the oven.
 10. The oven of claim 1, furthercomprising a second temperature sensor configured to sense temperatureof air in the cooking space and provide input to the controller.
 11. Theoven of claim 1, further comprising a limit-input user interfacecomprising a first input structure configured to allow a user to set theupper limit.
 12. The oven of claim 11, wherein the limit-input userinterface further comprises a second input structure configured to allowa user to increase the upper limit by a predetermined amount, and athird input structure configured to allow a user to decrease the upperlimit by a predetermined amount.
 13. The oven of claim 1, furthercomprising a user interface configured to automatically set the uppertemperature limit at about 350° F. plus a predetermined droop offset ofthe oven that is an inherent loss of heat energy involved in thetransfer of heat from the heating element to and through the air and ischaracteristic of the oven, when actuated by a user.
 14. The oven ofclaim 1, wherein the temperature sensor is in contact with a surface ofthe heating element.
 15. The oven of claim 1, which is a general purposeoven.
 16. The oven of claim 1, wherein the heating element is part of afan heater.
 17. The oven of claim 1, wherein the oven is free of heatingelements at a bottom of the oven.
 18. The oven of claim 1, wherein theheating element comprises a resistance heating element.
 19. The oven ofclaim 1, wherein the heating element comprises an induction heatingelement.